Selenium hexasulfide is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with formula Se₂S₆. Its molecular structure consists of a ring of two

selenium Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, ...

and six

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

atoms, analogous to the S₈

allotrope Allotropy or allotropism () is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of the elements. Allotropes are different structural modifications of an element: the ...

of sulfur ( cyclooctasulfur) and other selenium

sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...

s with formula Se_''n''S_8−''n''. There are several

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

s depending on the relative placement of the selenium atoms in the ring: 1,2 (with the two Se atoms adjacent), 1,3, 1,4, and 1,5 (with the Se atoms opposite).Arto Maaninen, Tristram Chivers, Masood Parvez, Jarkko Pietikäinen, and Risto S. Laitinen (1999), "Syntheses of THF Solutions of SeX₂ (X = Cl, Br) and a New Route to Selenium Sulfides Se_''n''S_8−''n'' (''n'' = 1−5): X-ray Crystal Structures of SeCl₂(tht)₂ and SeCl₂·tmtu". ''Inorganic Chemistry'', volume 38, issue 18, pages 4093–4097. It is an oxidizing agent. The 1,2 isomer can be prepared by reaction of chlorosulfanes and dichlorodiselane with

potassium iodide Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are us ...

carbon disulfide Carbon disulfide (also spelled as carbon disulphide) is a neurotoxic, colorless, volatile liquid with the formula and structure . The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical non ...

. The reaction produces also cyclooctaselenium Se₈ and all other eight-member cyclic selenium sulfides, except SeS₇, and several six- and seven-membered rings.Risto S. Laitinen, Pentti Pekone, Yrjö Hiltunen and Tapanin A. Pakkanen (1989), "The ⁷⁷S NMR spestroscopic Identification of Heterocyclic Selenium Sulfides Prepared by the Reactions of Chlorosulfanes and Dichlorodiselane with Potassium Iodide". ''Acta Chemica Scandinavica'', volume 43, pages 436-440.

References

Sulfides Selenium compounds Oxidizing agents Interchalcogens {{inorganic-compound-stub